1. Field of the Invention
The present invention relates to an electric pencil sharpener for shaving the tip of a pencil, particularly an electric pencil sharpener that is small and light in weight, still more particularly to a pencil sharpener that not only is small and light in weight but also has pencil-core adjustment capability.
2. Description of Related Art
Pencil sharpeners for office use can be classified as either electric (power) or manual. Some electric pencil sharpeners are driven by a battery and others are capable of automatically shaving (sharpening) a pencil using ac line current supplied from a wall socket. One feature of an electric pencil sharpener is that it operates automatically when a pencil is inserted into the sharpening hole. Although a rechargeable pencil sharpener is conceivable, a structure that is small and light in weight has been difficult to achieve.
Most manual pencil sharpeners are either small ones that can be carried on one's person or desktop ones that are manually operated by turning a crank. The small pencil sharpener is equipped with a single-edge cutting blade and sharpening is performed by turning either the pencil or the pencil sharpener by hand. The desktop pencil sharpener is used by inserting a pencil into the hole and turning the crank to perform sharpening.
A pencil sharpener with pencil-core adjustment capability is taught by Japanese Laid-open Patent Application No. 2003-154791. This is a manual pencil sharpener is equipped inward of cutting blades with a projection that a pencil strikes on when inserted. The thickness and length of the pencil-core can be adjusted by sliding this projection. Moving the projection deep into the cutting mechanism enables a pencil to strike on the projection immediately after shaving, thereby enabling sharpening of a pencil having a thick core. Shallow insertion enables deep shaving of the pencil, so that a pencil having a long core can be sharpened.
However, portable electric pencil sharpeners are not yet in widespread use and, notably, no portable electric pencil sharpener capable of adjusting core length has been made available.
A need has therefore been felt for development of a light-weight, compact pencil sharpener with core length adjustment capability that can automatically sharpen pencils.
Related background art can also be found in Japanese Laid-open Patent Application No. 2002-192891.